In the early art up until 1924 the patents which include an extra deck or decks of keys in close proximity to each other (such that one hand can simultaneously access multiple key decks), without exception involve coupled actions in which keys of the auxiliary deck or decks are mechanically linked to keys of the primary decks. This early art then, does not anticipate the advantage of complete independence of key actuation on all decks which is a highly desirable characteristic to include in a device of the nature I am describing herein.
Later on however, we see in the prior art beginning in 1924 the inclusion of multi-decked close proximity keyboards that do involve independent actuation in an auxiliary close proximity secondary key deck. However, this stage of the prior art fails to recognize the advantage of significantly shortening the front to back key surface distance in the lower secondary key decks relative to the front to back key surface distance in the primary deck.
In particular this phase of the prior art fails to recognize the importance of foreshortened auxiliary key decks in situations where largely piano-like lever action is maintained throughout a multi-decked keyboard array. Certain keyboards in the prior art have sought to create close proximity arrangements of auxiliary touchplate surfaces in combination with a primary piano keyboard by employing push button or electro-mechanical switch actions in the auxiliary decks. This is disadvantageous in situations where the feel of a piano-like lever action is desired throughout a multi-decked keyboard array.
In addition to possessing its own advantages such as enhanced one-hand simultaneous access to two main decks of keys, a foreshortened secondary main deck of keys makes the inclusion of a third main deck of keys very practical from the point of view of simultaneous one hand access to the three main decks of keys in the resulting multi-decked keyboard.
The post 1924 phase of the prior art then fails to describe a third main deck of keys in a multi-decked keyboard where close as possible proximity relationships are maintained between all decks and where largely piano-like and independently actuated levers are likewise maintained on all decks throughout a multi-decked keyboard array.
Another weakness of the prior art involves those designs which depart significantly from the normal arrangement of black and white keys. This is problematic in that it necessitates a relearning of scales and patterns and compositions that a musician has spent years memorizing on an ordinary keyboard.
Further incompleteness in the prior art concerns the manner in which the touchplate surfaces are connected to key levers. The use within one continuous structure of multiple rows of straight, largely piano-like wooden key levers (with said rows being motion independent of one another and disposed including appropriate yet minimal spacing in a parallel manner one row above the next), have never been employed in the prior art in conjunction with multiple decks of close proximity largely conventional piano-like touchplate surfaces.
Within the prior art, those inventions with multiple rows of conventional piano-like musical keyboards placed in very close proximity to each other, these said cases have either ignored the structure of the levers entirely or have employed mechanical means of actuation more complicated than or far different from the largely conventional piano-like levers of my invention or as previously mentioned said cases have employed means of coupling the secondary rows to the primary ones.
In the construction of contemporary keyboards for electronic interface, wood is often the preferred material for the construction of the key shanks in cases where an effort is made to replicate a piano-like feel in the action of the keyboard.
While prior art does anticipate the parallel stacking of rows of independent lever mechanisms that are connected to musical touchplate surfaces, the prior art does not anticipate the particular problems that arise when largely piano-like wooden key levers are to be arranged in parallel spaced levels one above the next for use in multi-decked keyboards of a design similar or exact to my own.
In particular, the placement of the stop rails (i.e., the stop means that define the downward extent of the key lever's arch of actuation at the front of the key lever) that are required for each main row of levers is crucial. In general, the closer the stop rail is to the front most point of the key lever, the better. If the stop rail is disposed away from the front of the key lever towards the fulcrum of the key lever, the stop rail has a tendency to act as a second fulcrum, especially when the key surface is struck near its front most point with strong force. This causes undesirable motion in the key lever.
This could be corrected by adapting the structure of the key lever system to include some auxiliary stop means probably disposed on the rearward side of the key lever but potentially contributing unnecessary costs and complications to the construction of the key lever. Even when this correction is made there will be a high amount of stress placed on the point on the key lever where it contacts a stop rail positioned significantly away from the front of the key lever especially when the key surface is struck near its front most point with strong force.
Thus a stop rail disposed away from the front of the key lever will force the manufacturer to take additional precautions in choosing materials strong enough to withstand such conditions of use. Forwardly placed stop rails than are clearly preferred yet this technical consideration has not been adequately addressed in the prior art.